Connectors have conventionally been used to electrically connect electronic components. A connector is such that electrical connection is established by bringing terminals provided to a socket and terminals provided to a header into contact with each other. The header and the socket are locked to each other using header-side retaining fittings and socket-side retaining fittings. With regard to the technique, PTL 1 discloses that the locking piece portion of each socket-side retaining fitting locks the locked portion of the corresponding header-side retaining fitting.